You could use the package Community Store. It's an e-commerce package that comes with several payment plugins (Paypal, Stripe, Authorize.net...)

You can set virtual products and select user groups where to put the buyers after they buy. With that in place, just use Concrete5 permission system to give access to users in specific groups.

Community Store is widely used but it's not in the marketplace. You can find it on Githubhttps://github.com/concrete5-community-store/community_store... and download official releases here:https://github.com/concrete5-community-store/community_store/release...

You can find extra plugins for it here:https://github.com/concrete5-community-store...